Support converting Array1<usize> (#98)

* Support converting Array1<usize>

* Review comments

Author: rth

src/types.rs

@@ -105,6 +105,17 @@ impl_type_num!(c32, Complex32, NPY_CFLOAT);
 impl_type_num!(c64, Complex64, NPY_CDOUBLE);
 impl_type_num!(*mut PyObject, PyObject, NPY_OBJECT);
 
+cfg_if! {
+    if #[cfg(all(target_pointer_width = "64", windows))] {
+            impl_type_num!(usize, Uint64, NPY_ULONGLONG);
+    } else if #[cfg(all(target_pointer_width = "64", not(windows)))] {
+            impl_type_num!(usize, Uint64, NPY_ULONG, NPY_ULONGLONG);
+    } else if #[cfg(all(target_pointer_width = "32", windows))] {
+            impl_type_num!(usize, Uint32, NPY_UINT, NPY_ULONG);
+    } else if #[cfg(all(target_pointer_width = "32", not(windows)))] {
+            impl_type_num!(usize, Uint32, NPY_UINT);
+    }
+}
 cfg_if! {
     if #[cfg(any(target_pointer_width = "32", windows))] {
         impl_type_num!(i32, Int32, NPY_INT, NPY_LONG);

tests/array.rs

@@ -249,7 +249,25 @@ macro_rules! small_array_test {
     };
 }
 
-small_array_test!(i8 u8 i16 u16 i32 u32 i64 u64);
+small_array_test!(i8 u8 i16 u16 i32 u32 i64 u64 usize);
+
+#[test]
+fn array_usize_dtype() {
+    let gil = pyo3::Python::acquire_gil();
+    let py = gil.python();
+    let locals = PyDict::new(py);
+
+    let a: Vec<usize> = vec![1, 2, 3];
+    let x = a.into_pyarray(py);
+    let x_repr = format!("{:?}", x);
+
+    let x_repr_expected = if cfg!(target_pointer_width = "64") {
+        "array([1, 2, 3], dtype=uint64)"
+    } else {
+        "array([1, 2, 3], dtype=uint32)"
+    };
+    assert_eq!(x_repr, x_repr_expected);
+}
 
 #[test]
 fn array_cast() {